Define Pydantic Telemetry Schemas

Create a Pydantic V2 model `SodiumTelemetry` with fields for `voltage_v`, `current_a`, `temp_c`, and `soc_pct`. Use Field validators to ensure values are within physical bounds (e.g., temp < 100). Then, initialize a `PydanticAI` agent that uses this model as its input context.